The isolated perfused lung (IPL), when compared to available in vitro and in vivo pulmonary systems, is a preparation that fulfills a majority of the ideal criteria for studying metabolism, binding and/or physiological response to xenobiotics. The IPL is an exceptionally useful method when there is a need for concurrent administration of multiple agents in different physical forms. Various details such as physiological and biochemical parameters and the construction of a small animal tracheal valve system are discussed.